51 « 
ACTJNOPIERTGIT. 
Mioplosus ahhreviatus^ E. D. Cope, Joe. cit. 1877, p. 814, and 
0^9. cit. 1884, p. 88. 
Mioplosus Joeani, E. D. Cope, loc. cit. 1877, p. 816, and op. dt. 
1884, p. 91, pi. xii. fig. 2. 
Mioplosus longus, E. D. Cope, loc. cit. 1877, p. 815, and op>. cit, 
1884, p. 90, pi. xii, fig. 3. ■ 
Mioplosus multidentatus, E. D Cope, Amer. Nat. vol. xxv. (1891), 
p. 657.—Lower Tertiary (?) ; Bee Hills, South Dakota. 
Mioplosus sauvogeanus, E. D. Cope, op. cit. 1884, p. 92, 
Genus PCRCA (Artedi), Linnaeus. 
[Syst. Nat. ed. 10, 1758, p. 289.] * 
Trunk laterally compressed and elongate-fusiform. Mouth large 
and protractile, and all teeth very small; preoperculum with 
serrations, those of lower limb antrorse ; operculum with one spine ; 
seven branchiostegal rays. Yertebrae 21 in the abdominal, 20 or 
21 in the caudal region. Two dorsal fins, the anterior with 12 to 
16 spines, the posterior with 2 or 3 spines and 12 to 15 articulated 
rays ; anal fin with 2 spines and 8 to 10 articulated rays ; caudal 
fin slightly forked. Scales small and lateral line complete. 
Existing in the freshwaters of the Northern hemisphere, and not 
known to be represented by any extinct species. 
The following specimens are referable to the typical Perea ^ 
fiwiatiUs, linn. H 
P. 8738. Preoperculum described and figured by E. T. Newton, 
Yert. Eorest Bed (Mem. Geol. Surv. 1882), p. 120, 
pi. xviii. fig. 1; Eorest Bed Series (Upper Ereshwater 
Bed), West Bunton, Norfolk, Savin Coll. 
P. 8734-35. Maxillae and scales ; West Bunton. Savin Coll. 
The fishes described as follows are not represented in the Col¬ 
lection, and their systematic position is uncertain ^— 
Perea (^Smerdis'l) lorenti, H. von Meyer, Neues Jahrb. 1845, 
p. 456, and Palaeontogr. vol. i. (1847), p. 105, pi. xii. 
fig. 3. (?) TcJitliyelites, Sir P. E gerton . Quart. Journ. 
Geol. Soc. vol. X. (1854), p. 374, pi. xiii.—Lower Tertiary ; 
Mokattam Hills, Cairo, Egypt. [Imperfect fish; Mann¬ 
heim Museum.] 
Perea macvacantha., T. C. Yunkler, Archiv. Mus. Teyler, vol. v. 
(1880), p. 94, pi. iii. figs. 7, 8.—Middle Oligocene; 
